The present invention relates to self-powered toy vehicles, and more particularly to coupling together of multi-unit toy vehicles.
So called "pulls" or load-pulling competitions have a long history. Originally horses pulled weighted wagons. Then tractors were used to pull loads. More recently four-wheel off-the-road vehicles have been used to pull loads. These competitions have been organized to a lesser and greater extent. There are rules and parameters for entry, and for participation; there are promoters, judges, entry fees and prizes; there are various classes or levels of competition based on such things as types and modifications of the vehicles, and the loads.
A recent development has been a variable-resistance sled which increases resistance the further the load is pulled. Such a sled comprises an elongated platform supported on wheels at its rear end. The platform is inclined upwardly toward its forward end which is supported by a skids. A weight receiving car or carrier rests upon the platform and is movable, as the sled is pulled, from the rear toward the front of the platform. This shifts weight on the platform from the rear wheels to the skids, and thus increases the resistance of the platform to being pulled forward. Contestants take turns using their vehicles to pull the sled. Contestants who are successful in pulling a given load the full length of the course, then go on to compete in the next round, pulling a greater load, etc. The contestant's pulling vehicles may be appropriately weighted in both the front and back to maintain wheel traction, according to competition rules. By this means, owners, dealers, and users of vehicles are able to demonstrate the power and pulling force of the vehicles manufactured, sold modified and/or maintained by them.
The development and production of a miniature self-powered 4-wheel drive toy vehicle sold under the trademark, "STOMPERS" by Schaper Manufacturing Co. provided the basis for competitions using toy replicas of the life-size or full-scale 4-wheel drive pulling vehicles. In these toy competitions rules have been established regarding class weights, etc. paralleling the rules for the life size competitions. In the toy vehicle competitions, contestants normally vie over a straight course or track of six to eight feet. The toy pulling vehicles pull a weighted sled similar to that described above either in a distance competition or in a timed competition. As with their life-size counterparts, there are rules relating to the amount of weight which may be loaded on the sled and/or on the front and rear ends of the pulling vehicle. Similarly, there are rules with respect to the nature of the coupling between the sled and the pulling vehicle; in particular there are rules with respect to the height of the hitch on the pulling vehicle to which the sled may be coupled.
However, due to the dramatically different orders of magnitude of force, weight, friction and other elements pertinent to the operation of a toy vehicle as contrasted with an actual full-scale vehicle, various couplings, structures and methods for utilizing such forces or operative elements must be designed, arranged, configured and proportioned differently than for their life-size counterparts. Further, because of cost considerations, the toy counterparts must achieve generally comparable ends in simplified or otherwise modified ways. Further, the toy vehicles have no drivers to compensate for events that may occur in the operation of the vehicles.
One particular need is for a means for coupling such toy pulling vehicles to a toy sled that is simple and economical to produce and to use while simulating the basic features of the full scale counterpart. A major problem which has been encountered in the past is the tendency of the unmanned self-powered toy pulling vehicle attached to the sled as by means such as a simple string to tend to jackknife or veer off to one side, especially when heavier loads are being pulling. In addition, it is desirable that the means for coupling the sled and pulling vehicle be adjustable or variable in the same ways as their full scale counterparts so as to emulate full scale competitions. It is also desirable that the same coupling means accomodate a plurality of different toy pulling vehicles.
These and other objects of the invention can better be understood by considering the following description.